JP2017097004A - Manufacturing method of optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of easily manufacturing an optical element that develops localized surface plasmon resonance.SOLUTION: Disclosed method of manufacturing an optical element includes: a first step to form a resin layer (2) constituted of a permeable resin; a second step to dispose metallic fine particles (3a) over the resin layer by applying a fluid dispersion, in which metallic fine particles (3a) are dispersed, over the resin layer; and a third step to form a new resin layer (4) by applying a permeable resin over the resin layer disposed with the metallic fine particles.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing an optical element that exhibits a nonlinear optical effect, for example, a method for manufacturing an optical element that exhibits a nonlinear optical effect based on localized surface plasmon resonance.

  Conventionally, nonlinear optical materials are known in which the electric polarization exhibits a second-order and third-order nonlinear response according to the electric field. Non-linear optical materials exhibit non-linear optical effects such as generation of optical harmonics and optical parametric amplification due to the above-mentioned non-linear response, so that they are widely used in laser oscillation devices, for example, as optical wavelength conversion elements and optical shutters. Has been. In particular, in recent years, it has attracted attention as an indispensable material for high-speed switching elements, optical logic gates, optical transistors, and the like, and research and development of various nonlinear optical materials has been actively conducted.

  Among these nonlinear optical materials, glass in which noble metal fine particles such as gold and silver are dispersed exhibits specific light absorption due to localized surface plasmon resonance in the visible light region, and further, the nonlinear optical response is also fast. It is expected as a powerful nonlinear optical material (see, for example, Non-Patent Document 1).

  As a method for producing a nonlinear optical material in which such localized surface plasmon resonance occurs, for example, a method using a melt quenching method (see Non-Patent Document 2) or a method using a sol-gel method (see Non-Patent Document 3). It has been known.

`` Ultrafast response of nonlinear refractive index of silver nanocrystals embedded in glass '', Y. Hamanaka, A. Nakamura, S. Omi, N. Del Fatti, F. Vallee, and C. Flytzanis, VOLUME 75, NUMBER 12, American institute of Physics, 20 SEPTEMBER 1999. `` Optical nonlinearities of a high concentration of small metal particles dispersed in glass: copper and silver particles '', K. Uchida, S. Kaneko, S. Omi, C. Hata, H. Tanji, Y. Asahara, AJ Ikushima, T. Tokizaki, and A. Nakamura, JOSA B, Vol. 11, Issue 7, pp. 1236-1243, 1994. `` Silver nanocrystals in silica by sol-gel processing '', G. Dea, A. Licciullia, C. Massaroa, L. Tapfera, M. Catalanob, G. Battaglinc, C. Meneghinid, and P. Mazzoldid, Journal of Non-Crystalline Solids, Volume 194, Issue 3, 1 February 1996, PP. 225-234. “Organic Nonlinear Optical (NLO) Materials”, [online], Tokyo Chemical Industry Co., Ltd., [October 19, 2015 search], Internet <URL: http : //www.tcichemicals.com/eshop/en/jp/category_index/03066/> “Cytop Optical Properties”, [online], Asahi Glass Co., Ltd., [October 19, 2015 search], Internet <URL: http://www.agc.com/kagaku/shinsei/cytop/optical.html> `` Multichannel Transmission Through a Gold Strip Plasmonic Waveguide Embedded in Cytop '', Behnam Banan, Mohammed Shafiqul Hai, Ewa Lisicka-Skrzek, Pierre Berini, and Odile Liboiron-Ladouceur, IEEE Photonics Journal, Vol. 5, Number 3, June 2013, 2201811 . "Organic nonlinear optical materials", Osamu Watanabe, Toyota Central R & D Review Vol.27 No.1 1992.3. “Measurement of specific surface area, pore distribution, particle size distribution”, Junji Noro, Kaoru Kato, Japan Society for Analytical Chemistry 2009. “Measurement of nanoparticle size and zeta potential of gold nanocolloid”, [online], Shimadzu Techno Research, Inc., [October 19, 2015 search], Internet <URL: http: //www.shimadzu-techno. co.jp/technical/colloidal_gold_zeta.html>

  However, the conventional method for manufacturing a nonlinear optical material in which localized surface plasmon resonance occurs using the melt quenching method or the sol-gel method has a problem that the manufacturing process becomes complicated and the manufacturing cost increases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a simple method for manufacturing an optical element that exhibits localized surface plasmon resonance.

  In the method of manufacturing an optical element according to the present invention, a first step of forming a resin layer (2) composed of a resin having transparency and a dispersion in which metal fine particles (3a) are dispersed are applied on the resin layer. Thus, a new resin layer (4) is formed by applying a resin having transparency to the second step of arranging the metal fine particles (3a) on the resin layer and the resin layer on which the metal fine particles are arranged. And a third step of forming.

  In the optical element manufacturing method, the second step and the third step may be repeated to form a plurality of metal fine particle layers (3_1 to 3_n) made of metal fine particles.

  In the method for manufacturing an optical element, all the resin layers may be formed of the same resin.

  In the above description, as an example, constituent elements on the drawing corresponding to the constituent elements of the invention are represented by reference numerals with parentheses.

  ADVANTAGE OF THE INVENTION According to this invention, the simple manufacturing method of the optical element which expresses localized surface plasmon resonance can be provided.

FIG. 1 is a diagram schematically showing a cross section of an optical element according to an embodiment of the present invention. FIG. 2A is a diagram for explaining a method of manufacturing an optical element according to an embodiment of the present invention. FIG. 2B is a diagram for explaining the manufacturing method of the optical element according to the embodiment of the present invention. FIG. 2C is a view for explaining the method of manufacturing the optical element according to the embodiment of the present invention. FIG. 3 is a diagram schematically showing a cross section of another optical element manufactured by the method for manufacturing an optical element according to an embodiment of the present invention. FIG. 4 is a diagram showing a measurement result of a spectral spectrum of a sample composed of a nanocolloid solution containing Au nanoparticles used in the method of manufacturing an optical element according to the embodiment of the present invention. FIG. 5 is a diagram showing a measurement result of a spectral spectrum of an optical element manufactured by the method for manufacturing an optical element according to the embodiment of the present invention. FIG. 6 is a diagram showing a measurement result of a spectral spectrum of an optical element manufactured by the method for manufacturing an optical element according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Configuration of optical element>
FIG. 1 is a diagram schematically showing a cross section of an optical element manufactured by the method for manufacturing an optical element according to an embodiment of the present invention.
In the drawing, as an example, a part of the laminated structure of the optical element according to the present embodiment is illustrated.

  An optical element 100 shown in the figure is an element that exhibits a nonlinear optical effect based on light absorption by localized surface plasmon resonance. For example, an optical wavelength conversion element, an optical shutter, a high-speed switching element, an optical logic gate, and light It can be applied to a transistor or the like.

As shown in the figure, the optical element 100 includes a substrate 1, a resin layer 2 formed on the substrate 1, metal fine particles 3a disposed on the resin layer 2, and a resin on which the metal fine particles 3a are disposed. And a resin layer 4 formed on the layer 2.
In this specification, a plane (layer) in which a plurality of metal fine particles 3 a are dispersed is referred to as a metal fine particle layer 3.
Specifically, the metal fine particle layer 3 is formed directly on the resin layer 2, and the resin layer 4 is formed to directly cover the metal fine particle layer 3. In other words, the metal fine particle layer 3 is formed such that the metal fine particles are in close contact with the resin and sandwiched between the resin layer 2 and the resin layer 4.

  The substrate 1 is made of a material having a high transmittance for at least visible light (for example, a transmittance of 80% or more). The substrate 1 is, for example, a quartz glass substrate.

  The resin layers 2 and 4 are made of a permeable resin. The resin is preferably a resin having a high transmittance (for example, a transmittance of 80% or more), a low refractive index and a low loss at least in the wavelength range targeted by the optical element 100. Examples of the resin include a fluorine cyclic polymer that can be easily applied onto the substrate 1.

The metal fine particle layer 3 is composed of a plurality of metal fine particles 3a uniformly dispersed on the resin. Each metal fine particle 3 a constituting the metal fine particle layer 3 is covered with a resin layer 4.
The metal fine particles 3a may be any metal material that exhibits surface plasmon resonance according to the use of the optical element 100. For example, a noble metal material such as gold (Au) and silver (Ag) or copper (Cu) is used. Can do.

  The particle diameter of the metal fine particle 3a may be a particle diameter that expresses a desired localized surface plasmon resonance. For example, an average particle diameter (measured by a known dynamic light scattering method (see Non-Patent Documents 8 and 9)) Average value of particle size distribution) X may be in the range of 10 nm ≦ X <100 nm.

<Optical element manufacturing method>
Next, a method for manufacturing an optical element according to the present embodiment will be described with reference to FIGS.

(1) Preparation of Substrate 1 First, a substrate 1 subjected to a base treatment is prepared. For example, a 0.7 mm thick quartz glass substrate that has been subjected to double-sided mirror polishing is cut by a dicing method or the like to produce a plurality of strip-shaped chips having a length of 2 cm and a width of 0.7 cm. Thereafter, each chip is washed with, for example, a strongly acidic solution, and then immersed in, for example, a hydrofluoric acid aqueous solution, and then washed with water to remove particles adhering to the surface of each chip. . One chip subjected to the above-described ground treatment is used as the substrate 1.

(2) Formation of resin layer 2 Next, the resin layer 2 is formed on the substrate 1 (first step).
Specifically, first, a solution containing an organic material constituting the resin layer 2 that is the first base material of the optical element 100 as a solute is prepared.

  More specifically, a solution in which a fluorinated cyclic polymer is dissolved in a fluorine-containing organic solvent is prepared, and a predetermined amount of the solution is collected. Thereafter, the collected solution is further diluted with the fluorine-containing organic solvent to prepare a fluorine-containing cyclic polymer solution. For example, CYTOP (manufactured by Asahi Glass Co., Ltd.) obtained by dissolving CYTOP (Cytop; registered trademark) made by Asahi Glass Co., Ltd. having a relative dielectric constant of 2.1, which is a fluorocyclic polymer, in a solvent CT-solv 180 manufactured by Asahi Glass Co., Ltd. as a fluorine-containing organic solvent. Solution CTL-813A is prepared. Then, 10 g of the CYTOP solution CTL-813A is collected and diluted with 30 g of the solvent CT-solv180. Thereby, a fluorine-containing cyclic polymer solution having a mass ratio of 1: 3 is obtained. In the present embodiment, the fluorine-containing cyclic polymer solution prepared by the above method is used.

  Here, CYTOP is well known as an organic material suitable for application, for example, as shown in Non-Patent Document 5, which has high visible light transmittance, low refractive index and low loss optical characteristics. For example, Non-Patent Document 6 discloses a plasmon optical waveguide using CYTOP.

  Next, in order to improve the adhesion between the substrate 1 and Cytop, HMDS (hexethyldisilazane) is applied on the substrate 1 by a known spin coating method and naturally dried. Thereafter, the fluorine-containing cyclic polymer solution prepared by the above-described method is applied onto the substrate 1 by a known spin coating method, and is subjected to heat treatment in an oven under predetermined conditions. As a result, as shown in FIG. 2A, a resin layer 2 composed of a fluorocyclic polymer (Cytop) is formed on the substrate 1. The conditions for the heat treatment will be described later.

(3) Formation of metal fine particle layer 3 Next, the metal fine particle layer 3 is formed on the resin layer 2 (second step).
Specifically, a dispersion liquid (nanocolloid solution) in which target metal fine particles are dispersed is applied onto the resin layer 2 formed in the first step by a spin coating method.

In the present embodiment, for example, a nano colloid solution in which gold (Au) nanoparticles having an average particle diameter of 30 nm are dispersed (Nippon Paint, Finesphere Gold W101) is used as the dispersion.
Thereafter, heat treatment is performed under predetermined conditions (for example, 100 ° C., OO hours) to evaporate the water in the nanocolloid solution. Thereby, as shown in FIG. 2B, the metal fine particle layer 3 composed of the gold nanoparticles can be formed on the resin layer 2.

(4) Formation of Resin Layer 4 Next, the resin layer 4 is formed on the metal fine particle layer 3 (third step).
Specifically, first, HMDS is applied by a known spin coating method on the laminated structure formed in the second step and on which the metal fine particle layer 3 is formed, and is naturally dried. Thereafter, similarly to the first step, the fluorine-containing cyclic polymer solution is applied onto the resin layer 2 on which the metal fine particle layer 3 is formed by a known spin coating method.

  Here, the resin layer 4 only needs to have a thickness that can sufficiently cover the metal fine particles 3a. For example, the resin layer 4 may have a thickness larger than the particle size of the metal fine particles 3a and not more than several tens of μm.

  Thereafter, heat treatment is performed in an oven under predetermined conditions. As a result, as shown in FIG. 2C, a resin layer 4 made of a fluorinated cyclic polymer (Cytop) covering the metal fine particles 3a is formed on the resin layer 2 on which the metal fine particle layer 3 is formed. . The conditions for the heat treatment will be described later.

  Through the above processing, the optical element 100 that exhibits a nonlinear optical effect based on light absorption by localized surface plasmon resonance can be manufactured.

<Optical device having a plurality of metal fine particle layers>
In the above-described example, the case where one metal fine particle layer is provided on the resin layer is shown, but a plurality of metal fine particle layers may be provided.

FIG. 3 is a diagram schematically showing a cross section of an optical element according to another embodiment of the present invention.
The optical element 101 shown in the figure has a plurality of metal fine particle layers 3_1 to 3_n (n is an integer of 1 or more), and, like the optical element 100, nonlinear optics based on light absorption by localized surface plasmon resonance. The effect is expressed.

  The optical element 101 is manufactured by repeatedly performing the second process (FIG. 2B) and the third process (FIG. 2C) after performing each process up to the third process in the same manner as the optical element 100 described above. be able to.

  Specifically, after the resin layer 4_1 is formed by the third step (FIG. 2C), the dispersion liquid in which the target metal fine particles 3b are dispersed on the resin layer 4_1 is formed by the spin coating method, as in the second step. The fine metal particle layer 3_2 is formed by applying and heat-treating. Thereafter, in the same manner as in the third step, HMDS was applied on the laminated structure on which the metal fine particle layer 3_2 was formed by a known spin coating method and naturally dried, and then the fluorine-containing cyclic polymer solution was spin-coated. The resin layer 4_2 is formed by applying the heat treatment on the resin layer 4_1 on which the metal fine particle layer 3_2 is formed. By repeating these processes a predetermined number of times, an optical element 101 in which a desired number of metal fine particle layers 3_1 to 3_n are stacked on the resin layer 2 can be manufactured.

<Optical device test results>
Next, the result of the spectroscopic test of the optical elements 100 and 101 manufactured by the manufacturing method described above will be shown.
In the spectroscopic test, a sample to be measured is sealed in a cuvette composed of a quartz glass cell, and the cuvette is set in a cell holder of a multi-channel small spectroscope (SEC 2000 manufactured by BAS). Absorbance (spectral spectrum) at each wavelength was measured. Water (H ₂ O) was used as a reference in the measurement.

FIG. 4 shows a sample (liquid) obtained by diluting a nanocolloid solution containing Au nanoparticles (manufactured by Nippon Paint, Finesphere Gold W101) used in the above-described production method with ultrapure water (H ₂ O). It is a figure which shows the measurement result of the spectral spectrum of a sample.
In the same figure, the spectral spectrum of each sample is shown in which the dispersion degree (dilution ratio) of Au nanoparticles in ultrapure water is used as a parameter. Specifically, reference numerals 401 to 404 represent spectral spectra when the dilution ratio is set to 5000 times, 2500 times, 500 times, and 400 times in volume ratio.

  From FIG. 4, it is understood that the peak of light absorption due to the localized surface plasmon resonance of Au appears in the vicinity of a wavelength of 560 nm. Further, it is understood that the peak value of light absorption increases as the dilution ratio of Au nanoparticles decreases (the degree of dispersion increases).

5 and 6 are diagrams showing the measurement results of the spectral spectrum of the optical element manufactured by the manufacturing method described above.
FIG. 5 shows the spectroscopic analysis of the optical elements 100 and 101 produced by performing the respective heat treatments in the first step (FIG. 2A) and the third step (FIG. 2C) in the above-described manufacturing method at a temperature of 100 ° C. for 15 minutes. The spectrum is shown. FIG. 6 shows optical elements 100 and 101 manufactured by performing the respective heat treatments in the first step (FIG. 2A) and the third step (FIG. 2C) in the above-described manufacturing method at a temperature of 185 ° C. for 90 minutes. The spectroscopic spectrum of is shown.

  5 and 6, reference numerals 501 and 601 represent spectral spectra of samples in which only the resin layer 2 as the first base material is formed on the substrate 1 and the metal fine particle layer 3 is not formed. Reference numerals 502 and 602 denote spectral spectra of the optical element 100 (see FIG. 1) in which the metal fine particle layer 3_n and the resin layer 4_n are provided one by one (n = 1), and reference numerals 503 and 603 denote the metal fine particle layer 3_n and 3 shows a spectral spectrum of an optical element 101 (see FIG. 3) in which three resin layers 4_n are provided (n = 3). Reference numerals 504 and 604 denote spectral spectra of the optical element 101 (see FIG. 3) in which five metal fine particle layers 3_n and five resin layers 4_n (n = 5) are provided. Reference numerals 505 and 605 denote metal spectra. 3 shows a spectrum of an optical element 101 (see FIG. 3) in which seven fine particle layers 3_n and seven resin layers 4_n are provided (n = 7).

  5 and 6, it is understood that a light absorption peak appears in the wavelength region near 560 nm in the optical elements 100 and 101 as well as the spectral spectrum of the nanocolloid solution containing Au nanoparticles shown in FIG. The Further, it is understood that the peak value of the spectral spectrum increases as the number (n) of the metal fine particle layers 3_n is increased, that is, as the concentration (density) of the metal fine particles 3b in the optical elements 100 and 101 is increased. Furthermore, it is understood that the amount of the localized surface plasmon to be expressed can be adjusted by changing the temperature and time when the resin constituting the resin layers 2, 4_1 to 4_n is cured.

  As described above, according to the method for manufacturing an optical element according to the present embodiment, by laminating the resin layers 2 and 4 having transparency and the metal fine particle layer 3 composed of metal fine particles, the localized surface plasmon resonance is used. Since the optical elements 100 and 101 that exhibit the nonlinear optical effect based on light absorption can be easily manufactured, the manufacturing process is simplified and the manufacturing cost is reduced as compared with the conventional manufacturing method using the melt quenching method or the sol-gel method. Can be suppressed.

  In particular, according to the present manufacturing method, the resin layers 2 and 4 and the metal fine particle layer 3 are formed by the coating method, so that compared with the case where the resin layers 2 and 4 and the metal fine particle layer 3 are formed by the sputtering method or the vacuum evaporation method. Manufacturing costs can be reduced.

  Moreover, in this manufacturing method, by forming the resin layer 2 and the resin layer 4 with the same resin, the manufacturing process is further facilitated, and the manufacturing cost is further reduced.

  Moreover, according to this manufacturing method, the amount of the localized surface plasmon to be expressed can be adjusted by changing the temperature and time when the resin constituting the resin layers 2, 4_1 to 4_n is cured, and the metal Since the peak value of the spectroscopic spectrum can be adjusted by changing the number of the fine particle layers 3, an optical element that exhibits a desired nonlinear optical effect can be easily manufactured.

  Although the invention made by the present inventors has been specifically described based on the embodiments, it is needless to say that the present invention is not limited thereto and can be variously modified without departing from the gist thereof. Yes.

  In the above embodiment, the case where CYTOP that does not express a nonlinear optical effect by itself is used as the resin layers 2 and 4 is exemplified, but the present invention is not limited to this, and an organic nonlinear optical material that exhibits a nonlinear optical effect (non-patent) Reference 7) may be used. For example, polydiacetylene or the like can be used as the resin layers 2 and 4.

  Moreover, in the said embodiment, although the case where the resin layers 2 and 4 were comprised from the same resin was illustrated, you may comprise the resin layer 2 and the resin layer 4 with a different kind of resin, respectively. For example, CYTOP may be used for the resin layer 2 and polydiacetylene may be used for the resin layer 4.

  Moreover, although the case where Au nanoparticles having an average particle diameter of 30 nanometers are used in the above-described embodiment is not limited to this, an aggregate of nanoparticles having an arbitrary particle diameter can also be used. . According to this, the peak value of the spectral spectrum can be adjusted.

  In addition, a spin coating method is used as a coating method for each of a solution (fluorine-containing cyclic polymer solution) containing a resin constituting the resin layers 2 and 4 and a nanocolloid solution containing the metal fine particles 3b constituting the metal fine particle layer 3. Although illustrated, it is not limited to this, For example, you may apply | coat by the well-known dipping method, the spray coat method, the inkjet method, or the roll coater method.

  Moreover, in the said embodiment, although the case where quartz glass was used as the board | substrate 1 was illustrated, it is not limited to this, It can function as a base which forms a resin layer similarly to quartz glass, Other materials with high transmittance (for example, plastics) may be used.

  DESCRIPTION OF SYMBOLS 100,101 ... Optical element, 1 ... Board | substrate, 2,4,4_1-4_n ... Resin layer, 3, 3_1-3_n ... Metal fine particle layer, 3a ... Metal fine particle.

Claims (7)

A first step of forming a resin layer composed of a permeable resin;
A second step of disposing metal fine particles on the resin layer by applying a dispersion in which the metal fine particles are dispersed on the resin layer;
And a third step of forming a new resin layer by applying a transparent resin on the resin layer on which the metal fine particles are arranged. A method for manufacturing an optical element. In the manufacturing method of the optical element of Claim 1,
The method of manufacturing an optical element, wherein the second step and the third step are repeated to form a plurality of metal fine particle layers made of the metal fine particles. In the manufacturing method of the optical element of Claim 1 or 2,
All the resin layers are formed with the same resin. The manufacturing method of the optical element characterized by the above-mentioned. In the manufacturing method of the optical element as described in any one of Claims 1 thru | or 3,
The method for manufacturing an optical element, wherein the resin is made of a fluorocyclic polymer. In the manufacturing method of the optical element as described in any one of Claims 1 thru | or 4,
The method for manufacturing an optical element, wherein the metal fine particles are made of at least one metal material of gold, silver, and copper. In the manufacturing method of the optical element as described in any one of Claims 1 thru | or 5,
Said 2nd process includes the process of apply | coating the said dispersion liquid by the spin coat method, the dipping method, the spray coat method, the inkjet method, or the roll coater method. The manufacturing method of the optical element characterized by the above-mentioned. In the manufacturing method of the optical element as described in any one of Claims 1 thru | or 6,
The first step and the third step include a step of applying a solution containing the resin as a solute by a spin coating method, a dipping method, a spray coating method, an ink jet method, or a roll coater method. Manufacturing method.

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